The car runs on Sony's Bio Battery which, in turn, gets its energy from breaking down sugars like those found in soda and fruit drinks. Therefore, the efficiency of the car depends on the liquid used (apparently, grape juice is the best). Obviously, a toy like this is intended as an eco-friendly alternative to electricity, but unless you are sifting through dumpsters for the residue in Red Bull cans, all you are really doing is wasting food. At any rate, the car is still in the prototype phase, so there is no word yet on when it might actually be available for sale. [Gigazine via Inhabitat]